Vessel Hulls

ABSTRACT

A hull for high speed marine vessels having a keel which is higher at the bow than at the stern and a center of gravity in the aft half of the hull is disclosed. Hulls in accordance with the present invention define an upper inclined trapezoidal reference plane and side surfaces which interconnected the edges of the keel with the reference plane to provide a hull having the aerodynamic characteristics of an inclined plane in motion.

United States Patent m1 Artemis 1 Jan. 28, 1975 i 1 VESSEL HULLS [76] Inventor: Annivas Artemis, 48 Dragoumis St..

Athens. Greece [22] Filed: Apr. 11, 1974 [2]] Appl. No.: 459,874

Related U.S. Application Data [63] Continuation-impart of Ser. No. 350,]44. April ll.

I973. abandoned.

[30] Foreign Application Priority Data Dec. l, I972 France 72.42839 [52] U.S. Cl. 114/56 [5]] Int. Cl B63b H18 [58] Field of Search ll4/56, 66.5 R, 66.5 H, ll4/43.5; 115/70; 9/1 R [56] References Cited UNITED STATES PATENTS 3.339.514 9/1967 Skuce ll ll4/66.5 R

3.763.810 l()/l973 Payne ..ll4/66.5R

FOREIGN PATENTS ()R APPLICATIONS l.l()6,44l 3/l968 Great Britain ll4/56 Primary Examiner-Trygve M. Blix Assistant E.\'uminer--Charles E. Frankfort 1 57 1 ABSTRACT A hull for high speed marine vessels having a keel which is higher at the bow than at the stern and a center of gravity in the aft half of the hull is disclosed. Hulls in accordance with the present invention define an upper inclined trapezoidal reference plane and side surfaces which interconnect the edges of the keel with the reference plane to provide a hull having the aerodynamic characteristics of an inclined plane in motion.

12 Claims, 10 Drawing Figures PATENTED M28195 3. 862 812 sum 2 or 2 'F/GSA 1 VESSEL I'IULLS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 350,144 filed Apr. I1, 1973 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the design-of motor' driven marine vessels. More specifically, this invention is directed to hulls for high speed vessels of the planing type. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art Vessels which develop sufficiently high speed whereby the normal water line of the forward part of the hull is raised above the surface, a mode of operation commonly referred to as planing, are known in the art. The conventional prior art hull is designed such that, in the planing mode, the vessel hull planes about 4. Such prior art vessels have been characterized by instability and handling difficulties when operated at high speeds on rough seas. Additionally, prior art planing vessels are also subjected to substantial shocks when operating at high speeds on rough seas and thus, under such conditions, must operate at reduced speeds. As a further disadvantage of prior arthull'designs, previous vessels have been characterized by excessive areas of contact with the water during the planing mode of operation whereby forward motion is seriously impeded by the resulting friction withthe water.

SUMMARY OF THE INVENTION The present invention overcomes the above briefly discussed and other deficiencies and disadvantages of the prior art by providing a novel and improved hull design for a high speed marine vessel. In accordance with the invention, a vessel hull is comprised of a keel and angularly oriented side surfaces which extend upwardly and outwardly from the keel; the side surfaces defining a substantially trapezoidal shaped reference plane. The trapezoidal reference plane is inclined at an angle of between 3.5 and 5 with respect to a horizontal plane in part defined by the portion of the keel which is immediately adjacent the stern of the hull; the reference plane being sloped upwardly to the bow end of the keel. The height of the trapezoid thus defined by the hull side surfaces is equal to the length of the hull and the major base of the trapezoid is smaller than its height. The longitudinal axis of the trapezoidal reference plane is positioned in the vertical plane of the longitudinal axis of the hull.

The above briefly described configuration defines a hull having opposite disposed side surfaces which are similarly oriented with respect to the inclined reference plane. Accordingly, the well known aerodynamic effect of an inclined plane is obtained when operating a vessel with such a hull at a high speed. The aerodynamic thrust, which is the sum of the pressures on the different points on the surface of the hull, will thus cause a vessel designed in accordance with the present invention to rise in relation to the surface of the body of water on which the vessel is being operated.

During operation a vessel designed in accordance with the present invention planes by about 4. Accordingly, in views of the inclined orientation of the upper reference plane, the various surfaces of the hull have an average orientation of approximately 8 10 in the direction of travel during high speed operation whereby maximum upward thrust is generated. Experience has shown that the hulls of the present invention, supported by this upward thrust, can travel at high speeds under variable surface conditions without loss of stability and are both easier to handle and suffer less violent shocks when compared to prior art hulls designed for similar operating conditions.

In a preferred embodiment of the invention the upper reference plane is inclined at an angle of 4 with respect to the horizontal. With this inclination of the reference plane, experimental results have permitted determination of the most desirable dimensions for a hull. Thus, the major base of the trapezoidal reference plane will be equal to /1 i 6% of the length of the keel while the minor base of the trapezoidal reference plane will be equal to 2/5 :2: 6% of the keel length. With respect to the keel, the difference in level between the highest and lowest parts thereof has been determined to be preferably equal to approximately one-fifth of the length of the keel. While the keel may have any conventional crosssection, the preferred cross-section will be the known V-shape with the angle between the two branches of the V being approximately 138 at a point corresponding to the maximum width of the keel. Under these conditions the width of the keel at its widest point is approximately equalto one-third of thelength of the hull.

Also in accordance with a preferred embodiment of the invention, the aft half of the keel will lie in a horizontal plane and will be characterized by a constant opening angle between the sides thereof. The forward half of the keel curve gradually upwards and will have an opening angle which gradually decreases in the forward direction.

Experimental results have shown that, at high speeds, there is a possibility of air flow between the surface of the water and the aft part of the hull of a vessel designed in accordance with the present invention. Accordingly, pursuant to a further embodiment of the invention, the hull side surfaces areshaped so as to impart, to a portion of the inclined reference plane corresponding to about one-third of the length of the reference plane, a different gradient. Thus, the rearwardly disposed portion of the reference plane may be raised or inclined by approximately 2 with respect to the remainder of the reference plane.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be better understood and its numerous objects and advantages will become apparent to those numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several figures and in which:

FIG. I is a schematic side elevation view of a vessel hull designed in accordance with the present invention;

FIG. 2 is a top plan view of the reference plane which determines the shape of the hull of the vessel of FIG.

FIG. 3A is a view taken along line 3A--3A of FIG. 1 depicting the aft portion of the hull of FIG. 1;

FIG. 3B is a view taken along line 3B3B of FIG. 1; FIG. 3C is a view taken along line 3C3C of FIG. 1', FIG. 3D is a view taken along line 3D3D of FIG.

FIG. 4 is a schematic front elevation view of a second embodiment of a hull in accordance with the present invention;

FIG. SA is a schematic side elevation view depicting DESCRIPTION OF THE PREFERRED EMBODIMENT I-Iulls designed in accordance with the present invention are intended for use for vessels which travel at speeds in excess of 40 kilometers per hour. As is well known, such high speed vessels will have their center of gravity in the aft half of the length of the hull and have to plane rapidly and over the greater part of the length of the hull in order to reduce friction with the water which seriously slows the vessel and detracts from its ability to maneuver. Referring to FIG. 1, the hull 1 has a preselected length l. The length l of the hull constitutes the basic design parameter from which the other dimensions of the hull are determined. Hull 1 comprises a keel 2 having a known configuration and characterized by advantageous hydrodynamic properties. In accordance with a preferred embodiment, as may most clearly be seen from FIGS. 3A-3D, the keel 2 has a V-shaped cross-section. The angle or included between the two branches or sides of keel 2 will be approximately l38 at the widest part of the keel. The aft portion 2' of the keel, extending over approximately half the length l, is rectilinear and horizontal. The forward part 2" of the keel gradually curves from a point P both upwardly and inwardly; the sides ofthe keel thus rejoining or merging at point P1 at the bow of the hull. From the point P the angle a between the two sides of the keel is gradually reduced in the forward direction. The width d of the keel at its widest point, which in the disclosed embodiment is situated at the stern of hull l, is equal to one-third of the length 1. As may best be seen from FIG. 3A, proceeding forwardly from the stern of the hull the width d is gradually reduced to the point P1 at the bow where the two sides of the keel merge. The curve of forward portion 2" of the keel and the evolution of the width d at various points along the length of the hull are determined in a known manner to obtain the desired hydrodynamic characteristics when the keel is immersed over a large part of its length as would be the case with the vessel traveling at a reduced speed.

The upper portion of hull l; i.e., that portion which may be employed to connect the hull to the deck or other super-structure of a vessel, is defined by a reference plane 3. In the disclosed embodiment, the reference plane 3 is represented as constituting the deck of the vessel and thus comprising an actual surface. In accordance with the present invention reference plane 3 in inclined with respect to the horizontal H by an angle B in the range of approxirnately 3.5 to the preferred angle B being 4. The highest point of the reference plane 3 is situated at the level of point P1 in the bow of the hull. As may be seen from FIGS. 2 and 3, the reference surface or plane is of generally trapezoidal configuration. The height [1 of the trapezoid ABCD, as defined by the hull side walls 5, is equal to the length l of the hull and the longitudinal axis of the trapezoid is situated in a vertical plane through the longitudinal axis of the hull. The minor base AB of the trapezoid which comprises the reference plane is positioned in the bow of the vessel while the major base CD is situated at the vessel stern. In accordance with the preferred embodiment, the height h of the trapezoid is greater than the length of base CD. Experiments have shown that particularly advantageous results are obtained when the base CD is equal to 0.75h and the base AB is equal to 0.4h. Also, experiments have indicated that the height h of base AB of the trapezoidal reference plane 3 above the lowest part of keel is preferably equal to one-fifth of the length [of the hull.

The upper side portions of the hull; i.e., the portions which extend upwardly and outwardly from the keel to define the reference plane; are comprised of members 5 as shown in FIGS. 1 and 3. The side members 5 of the hull thus consist of surfaces by which the edges, BC, CD and AD of reference plane 3 are connected to corresponding edges PIF, FE and EH of keel 2. These connecting or upper side portions 5 of the hull will have aerodynamic characteristics very similar to those of an inclined plane in motion. Accordingly, during operation, the bow cuts the mass of air in front of the vessel according to a horizontal plane insuring an aerodynamic thrust directed upwardly on the surfaces 5. This results in the hull planing at a relatively low speed and, at full speed, the hull will reach an angle of inclination of about 8 with respect to the horizontal. Even with an angle of inclination in the range of 7.5 to 9 in the direction of travel, the vessel having a hull designed in accordance with the present invention is stable due to the aerodynamic'configuration of the upper side portions 5 of the hull. Additionally, the hull of the present invention offers far less resistance to air than previous designs.

Experiments have shown that, at high speeds, air may rush in between the aft part of the hull and the surface of the water thereby producing a braking effect. Thus, as shown in FIG. 4 and indicated by the broken line 3 in FIG. 1, the aft part of the reference plane 3 may be raised by about 2 with respect to the remainder of plane 3; i.e., the reference plane may in practice be a pair of interconnected planar surfaces with different angles of inclination with respect to a plane H which, with the hull at rest, will be horizontal.

In the disclosed embodiment the novel hull is provided with a vertical stem 6. It will be understood, however, that the configuration of the vessel stern may vary in accordance with the type of motor employed. Thus, by way of example only, stern 6 may have rounded corners as indicated at'3" in FIG. 2.

To summarize the preceding, the hull of the present invention has been designed in the interest of obtaining advantageous behavior in the air and simultaneously adequate hydrodynamic behavior. Thus, the present invention is a hull that presents very small resistance to the forward motion of a vessel and provides strong up ward lift. In designing the present hull aerodynamic behavior, and specifically the fluid mechanics concerning wing profiles, has been taken into consideration since a boat hull must be assimilated to an airfoil profile. Incidence angles for wing profiles vary normally in the range of l0l5. For a boat hull, which must also be characterized by convenient hudrodynamic behavior, an incidence angle of about was chosen as the basis for initiating design. Starting from this incidence angle norm, it is important to control the over-pressure exerted on the hull and the depression exerted on the bridge in the interest of avoiding a strain on the hull. Thus, when establishing the various dimensions of a hull, it is necessary to proceed from certain limits concerning the height and length of the hull so as to obtain a vessel having reasonable dimensions. Accordingly, surface measurements are taken in the transverse direction of the hull rather than in the longitudinal direction since. if measurements proceeded in the longitudinal direction, an unreasonable reduction of the height of the hull would be obtained or the resulting hull would have an undue vertical orientation which could not produce the requisite lift.

With the preceding general considerations in mind, the hull of the present invention has a number of critical dimensions. A first of these dimensions is the inclination angle of 3.55, and preferably 4", for the trapezoidal reference plane; the inclination angle being measured with respect to the surface of the water with the hull at rest. Additionally, the dimensions of the trapezoidal reference plane must be a function of the length of the keel; i.e., the small base of the trapezoid must be equal to 2/5 i 6% and the large base must be equal to :t 6% of the length of the keel. It is also desirable that the opening angle of the V-shaped keel be approximately 138 at the largest part thereof; the largest part typically being at the stern of the vessel. The width of the keel where it transcribes its maximum opening angle should be equal to approximately one-third the length of the hull. Finally, the vertical difference between the highest and lowest portions of the hull, with respect to the horizontal, should preferably be equal to approximately one-fifth of the length of the hull.

The inclination angle is chosen to produce an inclination of the hull, when operating at high speed, in the range of 75 to 9. As may be seen by joint consideration of FIGS. 5A, 5B and 5C, this range of inclination angles produces optimum performance from an aerodynamic point of view. The slight incline of the hull permits an increase in stability thus making reinforcement unnecessary.

The dimensions of the reference plane have been chosen to insure that the rear surface of the hull forms a prolongation of the wings of the hull without inflexion toward the top or bottom with respect to the limit points E and F indicated in FIG. 3A. A strong inclination towards the top of side portions F-C and E-D would reduce the downward aerodynamic push at the rear of the hull while an inflexion toward the bottom of the hull would produce engulfing of the air between the hull and the surface of the water. The dimensions of the small base of the trapezoidal reference plane is determined as a function of the center of gravity of the hull. If the dimension AB of FIG. 2 is changed with respect to the large base CD of the reference plane the center of the aerodynamic push moves forward or backward faster" than the center of gravity of the hull. Thus, it may be seen that the dimensions of the trapezoidal reference surface are selected in the interest of bringing the center of the aerodynamic push as close as possible to the center of gravity thereby obtaining dynamic equilibrium in the longitudinal direction of the hull at high speeds. The margin of: 6% permits slight modification of the position of the center of aerodynamic push as a function of the possible variations of the center of gravity; the latter variations being expected as a consequence of the tolerances observed during construction.

A keel opening angle of l38 has been found to be advantageous for hydrodynamic reasons and produces a very favorable gradient of the side surfaces of the hull. The selection of the maximum width of the hull as a function of hull length determines, with the opening angle of 138, a limit on the height of the floating line." This floating line" height defines the surfaces of the hull as a function of the trapezoidal reference plane. Restated, the selection of a keel width, at the widest point thereof, which is approximately one-third the length of the hull permits the hull to have large aerodynamic surface portions. The height of the hull is determined in the interest of obtaining convenient gradients of the surfaces thereof and thus the relationship between the length of the hull and the difference in height between the highest and lowest portions thereof is dictated by practical considerations.

Referring again to FIG. 5A, 5B and 5C, and taking into consideration the discussion above of FIGS. 1-4, it will now be obvious to those skilled in the art that the hull of the present invention has a number of significant advantages when compared to previous high speed vessel designs. Thus, by way of example, the present invention is characterized by better aerodynamic support when planing than prior art hulls. Additionally, the hull of the present invention is characterized by exceptional dynamic stability with respect to its longitudinal axis as a result ofthe great inertia moment due to its width. As clearly shown in FIG. 5, free flow of air at the sides of the hull is permitted in the case of the present invention thus obviating the problem of over-turning because of over-pressure which has previously occurred when prior art vessels traveled at a high rate of speed into a head wind. If a vessel employing the hull of the present invention lifts off of the water because of a wave shock and starts a rotation about its longitudinal axis, which would be the beginning of an over-turn in the transversal direction, an increase in aerodynamic pressure on the surface of the hull which is on the side of the direction of rotation will result due to the shape of the hull and, conversely, a pressure decrease will result on the opposed side. This pressure differential will tend to cause the vessel to come back to its original position. This same phenomenon is produced if the vessel, while proceeding normally, initiates a gradient for any reason. For example, if a vessel employing the hull of the present invention makes a very tight turn at a high speed the hull reference plane presents a large surface toward the center of the turn and the opposing surface receives the aerodynamic pressure which prevents the creation of a large drag or over-turn of the vessel.

While a preferred embodiment has been shown and described various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

l. A bull for a ship intended for high speed operation comprising:

keel means, said keel means including an elongated keel having a V-shaped cross-section, said keel means having a longitudinal axis, the forward end of said keel defining the bow of the hull and extending above a horizontal plane through the oppositely disposed end of the keel, said keel having a width equal to approximately one-third the length of the hull at its widest point;

hull side surface defining members extending outwardly from respective edges of said V-shaped keel, said side surface defining members being inclined with respect to a vertical plane extending through the longitudinal axis of said keel means; and

trapezoidal reference plane defining means, said reference plane defining means including the edges of said side surface defining members disposed oppositely to the edges of said members which are in contact with said keel, said reference plane being inclined at an angle in the range of 3.55 with respect to said horizontal plane and having its highest edge at the level of the bow end of said keel means, the trapezoid defined by said reference plane defining means having a longitudinal axis positioned in said vertical plane, the major base of said trapezoid defined by said reference plane defining means being equal in length to A i 6% of the length of said keel means and the minor base of the trapezoid being equal in length to 2/5 t 6% of the length of said keel means, said minor base intersecting the bow end of said keel means.

2. The apparatus of claim 1 wherein said reference plane is inclined at an angle of approximately 4 with respect to the horizontal;

3. The apparatus of claim 1 wherein the forward end of said keel means is vertically spaced above the aft end of said keel means by a distance equal to approximately one-fifth of the length of said keel means.

4. The apparatus of claim 1 wherein the angle included between the two sides of said V-shaped keel means is approximately 138 at a point corresponding to the maximum width of the keel.

5. The apparatus of claim 4 wherein said aft half of the keel lies in said horizontal plane and the forward 8 half of the V-shaped keel curves gradually upwards and is characterized by an angle between the diverging sides thereof which gradually decreases in the forward direction.

6. The apparatus of claim wherein the forward end of said keel means is vertically spaced above the aft end a of said keel means by a distance equal to approximately one-fifth of the length of said keel means.

7. The apparatus of claim 1 wherein said reference plane defining means further comprises:

a rearwardly disposed portion, corresponding to approximately one-third the length of the trapezoid. inclined upwardly toward the stern of the hull at an angle of approximately 2 with respect to the remainder of the reference plane.

8. The apparatus of claim 1 wherein the aft half of the keel lies in said horizontal plane and the forward half of the V-shaped keel curves gradually upwards and is characterized by an angle between the diverging sides thereof which gradually decreases in the forward direction.

9. The apparatus of claim 8 wherein said reference plane defining means further comprises:

a rearwardly disposed portion, corresponding to approximately one-third the length of the trapezoid, inclined upwardly toward the stern of the hull at an angle of approximately 2 with respect to the remainder of the reference plane.

10. The apparatus of claim 9 wherein the forward end of said keel means is vertically spaced above the aft end of said keel means by a distance equal to approximately one-fifth of the length of said keel means.

11. The apparatus of claim 10 wherein the angle included between the two sides of said V-shaped keel means is approximately 138 at a point corresponding to the maximum width of the keel.

12. The apparatus of claim 9 wherein the angle included between the two sides of said V-shaped keel means is approximately l38 at a point corresponding to the maximum width of the keel. 

1. A hull for a ship intended for high speed operation comprising: keel means, said keel means including an elongated keel having a V-shaped cross-section, said keel means having a longitudinal axis, the forward end of said keel defining the bow of the hull and extending above a horizontal plane through the oppositely disposed end of the keel, said keel having a width equal to approximately one-third the length of the hull at its widest point; hull side surface defining members extending outwardly from respective edges of said V-shaped keel, said side surface defining members being inclined with respect to a vertical plane extending through the longitudinal axis of said keel means; and trapezoidal reference plane defining means, said reference plane defining means including the edges of said side surface defining members disposed oppositely to the edges of said members which are in contact with said keel, said reference plane being inclined at an angle in the range of 3.5*-5* with respect to said horizontal plane and having its highest edge at the level of the bow end of said keel means, the trapezoid defined by said reference plane defining means having a longitudinal axis positioned in said vertical plane, the major base of said trapezoid defined by said reference plane defining means being equal in length to 3/4 + OR - 6% of the length of said keel means and the minor base of the trapezoid being equal in length to 2/5 + OR - 6% of the length of said keel means, said minor base intersecting the bow end of said keel means.
 2. The apparatus of claim 1 wherein said reference plane is inclined at an angle of approximately 4* with respect to the horizontal.
 3. The apparatus of claim 1 wherein the forward end of said keel means is vertically spaced above the aft end of said keel means by a distance equal to approximately one-fifth of the length of said keel means.
 4. The apparatus of claim 1 wherein the angle included betweEn the two sides of said V-shaped keel means is approximately 138* at a point corresponding to the maximum width of the keel.
 5. The apparatus of claim 4 wherein said aft half of the keel lies in said horizontal plane and the forward half of the V-shaped keel curves gradually upwards and is characterized by an angle between the diverging sides thereof which gradually decreases in the forward direction.
 6. The apparatus of claim 5 wherein the forward end of said keel means is vertically spaced above the aft end of said keel means by a distance equal to approximately one-fifth of the length of said keel means.
 7. The apparatus of claim 1 wherein said reference plane defining means further comprises: a rearwardly disposed portion, corresponding to approximately one-third the length of the trapezoid, inclined upwardly toward the stern of the hull at an angle of approximately 2* with respect to the remainder of the reference plane.
 8. The apparatus of claim 1 wherein the aft half of the keel lies in said horizontal plane and the forward half of the V-shaped keel curves gradually upwards and is characterized by an angle between the diverging sides thereof which gradually decreases in the forward direction.
 9. The apparatus of claim 8 wherein said reference plane defining means further comprises: a rearwardly disposed portion, corresponding to approximately one-third the length of the trapezoid, inclined upwardly toward the stern of the hull at an angle of approximately 2* with respect to the remainder of the reference plane.
 10. The apparatus of claim 9 wherein the forward end of said keel means is vertically spaced above the aft end of said keel means by a distance equal to approximately one-fifth of the length of said keel means.
 11. The apparatus of claim 10 wherein the angle included between the two sides of said V-shaped keel means is approximately 138* at a point corresponding to the maximum width of the keel.
 12. The apparatus of claim 9 wherein the angle included between the two sides of said V-shaped keel means is approximately 138* at a point corresponding to the maximum width of the keel. 